The surface the draw loop needs from R-32's appearance program (ParticleAppearanceProgram): the billboard contract plus its two feature switches.
ParticleAppearanceProgram
Uploads one system's world matrix.
Uploads the camera's projection, once per view.
Selects the soft-particle depth comparison (off at this tier).
Optional
Selects whether this draw samples the bound particle texture.
Uploads the camera's view matrix, once per view.
Makes this the current program.
The surface the draw loop needs from R-32's appearance program (
ParticleAppearanceProgram): the billboard contract plus its two feature switches.